Chapter 3 - The Cell

Question 1

Which of the following individuals argued in favor of the theory of spontaneous generation?

A) Francesco Redi.
B) Louis Pasteur.
C) John Needham.
D) Lazzaro Spallanzani.

Answer 1

Correct Answer: C) John Needham.

Explanation: Needham believed that microbes arose spontaneously after boiling broth, failing to realize contamination could occur; his flawed experiment initially supported spontaneous generation.

Question 2

Which of the following individuals is credited for definitively refuting the theory of spontaneous generation using broth in swan-neck flasks?

A) Aristotle.
B) Jan Baptista van Helmont.
C) John Needham.
D) Louis Pasteur.

Answer 2

Correct Answer: D) Louis Pasteur.

Explanation: Pasteur’s swan-neck flask experiment showed that boiled broth remained sterile unless exposed to airborne microorganisms, proving life arises from existing life (biogenesis).

Question 3

Which of the following scientists experimented with raw meat, maggots, and flies in an attempt to disprove the theory of spontaneous generation?

A) Aristotle.
B) Lazzaro Spallanzani.
C) Antonie van Leeuwenhoek.
D) Francesco Redi.

Answer 3

Correct Answer: D) Francesco Redi.

Explanation: Redi’s experiments using covered and uncovered jars of meat demonstrated that maggots only appeared when flies had access, refuting spontaneous generation for larger organisms.

Question 4

Who was the earliest recorded scholar to articulate the theory of spontaneous generation?

A) Acrion.
B) Agamemnon.
C) Aedesia.
D) Aristotle.

Answer 4

Correct Answer: D) Aristotle.

Explanation: Aristotle first proposed that life could arise spontaneously from nonliving matter, such as flies from decaying meat—a belief that persisted for centuries.

Question 5

In 1745, John Needham published a report describing experiments in which he briefly boiled broth containing plant or animal matter, sealed the flasks, and later found microbial growth. What is the likely explanation for this result?

A) All of the existing microbes had been killed.
B) Needham likely did not boil the broth enough to kill all preexisting microbes.
C) None of these.
D) Spontaneous generation.

Answer 5

Correct Answer: B) Needham likely did not boil the broth enough to kill all preexisting microbes.

Explanation: Needham’s boiling time was insufficient to sterilize the broth, allowing residual microorganisms to grow and falsely appear as if they arose spontaneously.

Question 6

Which of the following individuals did not contribute to the establishment of cell theory?

A) Girolamo Fracastoro.
B) Matthias Schleiden.
C) Robert Remak.
D) Robert Hooke.

Answer 6

Correct Answer: A) Girolamo Fracastoro.

Explanation: Fracastoro proposed germ transmission of disease, but he was not involved in formulating cell theory; Schleiden, Remak, and Hooke were key contributors to its development.

Question 7

Whose proposal of the endosymbiotic theory of mitochondrial and chloroplast origin was ultimately accepted by the greater scientific community?

A) Rudolf Virchow.
B) Ignaz Semmelweis.
C) Lynn Margulis.
D) Theodor Schwann.

Answer 7

Correct Answer: C) Lynn Margulis.

Explanation: Margulis revived and provided strong evidence for the endosymbiotic theory, showing that mitochondria and chloroplasts evolved from symbiotic bacteria.

Question 8

Which of the following developed a set of postulates for determining whether a particular disease is caused by a particular pathogen?

A) John Snow.
B) Robert Koch.
C) Joseph Lister.
D) Louis Pasteur.

Answer 8

Correct Answer: B) Robert Koch.

Explanation: Koch’s postulates established experimental criteria linking specific microbes to specific diseases, foundational to the germ theory of disease.

Question 9

The English scientist Robert Hooke first used the term “(BLANK)” in 1665 to describe the small chambers within cork that he observed under a microscope of his own design.

A) Ribosomes.
B) Microsomes.
C) Organisms.
D) Cells.

Answer 9

Correct Answer: D) Cells.

Explanation: Robert Hooke coined the term “cells” after observing cork under his microscope, noting that the box-like structures resembled small rooms or “cellulae.”

Question 10

In what decade did we recognize the modern cell theory?

A) 1850s.
B) 1940s.
C) 1950s.
D) 1840s.

Answer 10

Correct Answer: A) 1850s.

Explanation: By the 1850s, the modern cell theory was established, combining the findings of Schleiden, Schwann, and Virchow that all living things are composed of cells and all cells arise from existing cells.

Question 11

Who was the first scientist to articulate the endosymbiotic hypothesis?

A) Andreas Schimper.
B) Konstantin Mereschkowski.
C) Ivan Wallin.
D) Robert Brown.

Answer 11

Correct Answer: B) Konstantin Mereschkowski.

Explanation: Mereschkowski proposed that certain eukaryotic organelles, such as chloroplasts, originated from symbiotic relationships between primitive eukaryotes and bacteria.

Question 12

Who conducted studies to track the source of cholera outbreaks in London, which ultimately resulted in the first known public health response to an epidemic?

A) Joseph Lister.
B) Ignaz Semmelweis.
C) John Snow.
D) Louis Pasteur.

Answer 12

Correct Answer: C) John Snow.

Explanation: John Snow traced cholera cases to a contaminated water pump on Broad Street, linking disease to waterborne pathogens and pioneering epidemiology.

Question 13

Which of the following terms refers to a prokaryotic cell that is comma shaped?

A) Coccus.
B) Coccobacillus.
C) Vibrio.
D) Spirillum.

Answer 13

Correct Answer: C) Vibrio.

Explanation: Vibrio bacteria have a curved, comma-like shape, distinct from cocci (spherical) or spirilla (spiral).

Question 14

Which bacterial structures are important for adherence to surfaces?
(Select all that apply.)

A) Endospores.
B) Cell walls.
C) Fimbriae.
D) Capsules.
E) Flagella.

Answer 14

Correct Answers: C) Fimbriae, D) Capsules.

Explanation: Fimbriae and capsules help bacteria adhere to surfaces and host tissues, playing key roles in colonization and biofilm formation.

Question 15

Which of the following cell wall components is unique to gram-negative cells?

A) Lipopolysaccharide.
B) Teichoic acid.
C) Mycolic acid.
D) Peptidoglycan.

Answer 15

Correct Answer: A) Lipopolysaccharide.

Explanation: Gram-negative bacteria possess an outer membrane containing lipopolysaccharides (LPS), which are absent in gram-positive bacteria.

Question 16

Which of the following terms refers to a bacterial cell having a single tuft of flagella at one end?

A) Monotrichous.
B) Amphitrichous.
C) Peritrichous.
D) Lophotrichous.

Answer 16

Correct Answer: D) Lophotrichous.

Explanation: Lophotrichous bacteria have multiple flagella at one end, allowing more powerful directional movement compared to a single monotrichous flagellum.

Question 17

Bacterial cell walls are primarily composed of which of the following?

A) Phospholipid.
B) Protein.
C) Carbohydrate.
D) Peptidoglycan.

Answer 17

Correct Answer: D) Peptidoglycan.

Explanation: Peptidoglycan, a mesh-like polymer of sugars and amino acids, provides rigidity and protection to bacterial cell walls and is unique to bacteria.

Question 18

Which of the following terms refers to a prokaryotic cell that is spiral shaped?

A) Coccobacillus.
B) Vibrio.
C) Spirillum.
D) Coccus.

Answer 18

Correct Answer: C) Spirillum.

Explanation: A spirillum is a rigid, spiral-shaped bacterium, distinct from vibrio (comma-shaped) and coccus (spherical) forms.

Question 19

(BLANK) is a form of transport used by bacteria, but not by eukaryotic cells, to move materials across the cell membrane and into the cell.

A) Group translocation.
B) Ciliated translocation.
C) Solo translocation.
D) Lysification.

Answer 19

Correct Answer: A) Group translocation.

Explanation: Group translocation chemically modifies molecules as they enter the bacterial cell, preventing them from diffusing back out—unique to prokaryotes.

Question 20

(BLANK) cells lack a nucleus.

A) Plant.
B) Animal.
C) Prokaryotic.
D) Eukaryotic.

Answer 20

Correct Answer: C) Prokaryotic.

Explanation: Prokaryotic cells lack a membrane-bound nucleus, with their genetic material located in the nucleoid region instead.

Question 21

When the concentration of solutes differs across a membrane, water moves from the side with lower solute concentration to the side with higher solute concentration until equilibrium is reached. This diffusion of water is called (BLANK).

A) Potential.
B) Diffusion.
C) Membrane.
D) Osmosis.

Answer 21

Correct Answer: D) Osmosis.

Explanation: Osmosis is the passive movement of water across a semipermeable membrane driven by differences in solute concentration.

Question 22

Which of the following organelles is not part of the endomembrane system?

A) Endoplasmic reticulum.
B) Golgi apparatus.
C) Lysosome.
D) Peroxisome.

Answer 22

Correct Answer: D) Peroxisome.

Explanation: Peroxisomes are involved in oxidation reactions and lipid metabolism but function independently of the endomembrane system.

Question 23

Which type of cytoskeletal fiber is important in the formation of the nuclear lamina?

A) Microfilaments.
B) Intermediate filaments.
C) Microtubules.
D) Fibronectin.

Answer 23

Correct Answer: B) Intermediate filaments.

Explanation: The nuclear lamina is composed of lamin proteins, a type of intermediate filament that provides structural support to the nucleus.

Question 24

Sugar groups may be added to proteins in which of the following?

A) Smooth endoplasmic reticulum.
B) Rough endoplasmic reticulum.
C) Golgi apparatus.
D) Lysosome.

Answer 24

Correct Answer: C) Golgi apparatus.

Explanation: The Golgi apparatus modifies proteins received from the ER, adding carbohydrate groups (glycosylation) and sorting them for transport.

Question 25

Which of the following structures of a eukaryotic cell is not likely derived from an endosymbiotic bacterium? A) Mitochondrial DNA. B) Mitochondrial ribosomes. C) Inner membrane. D) Outer membrane.

Answer 25

Correct Answer: D) Outer membrane. Explanation: The outer mitochondrial membrane originates from the host cell’s plasma membrane, while the inner membrane and genetic material reflect bacterial ancestry.

Question 26

Which type of nutrient uptake involves the engulfment of small dissolved molecules into vesicles? A) Active transport. B) Pinocytosis. C) Receptor-mediated endocytosis. D) Facilitated diffusion.

Answer 26

Correct Answer: B) Pinocytosis. Explanation: Pinocytosis ('cell drinking') is a form of endocytosis where the cell engulfs extracellular fluid and small dissolved molecules into vesicles.

Question 27

Which of the following is not composed of microtubules? A) Desmosomes. B) Centrioles. C) Eukaryotic flagella. D) Eukaryotic cilia.

Answer 27

Correct Answer: A) Desmosomes. Explanation: Desmosomes are anchoring junctions made of intermediate filaments, not microtubules, while centrioles, flagella, and cilia are microtubule-based structures.

Question 28

Which of the following are anchored into the plasma membrane by a basal body composed of nine triplets of microtubules? A) Eukaryotic flagella. B) Eukaryotic cilia. C) Prokaryotic flagella only. D) Eukaryotic cilia only.

Answer 28

Correct Answers: A) Eukaryotic flagella, B) Eukaryotic cilia. Explanation: Both eukaryotic flagella and cilia are anchored by basal bodies with nine microtubule triplets, structurally similar to centrioles, enabling coordinated movement.

Question 29

Eukaryotic cells possess a (BLANK), which is surrounded by a complex nuclear membrane that houses the (BLANK). A) Microglia, mitochondria. B) Mitochondria, prokaryotes. C) Nucleus, DNA. D) DNA, nucleus.

Answer 29

Correct Answer: C) Nucleus, DNA. Explanation: Eukaryotic cells contain a true nucleus enclosed by a nuclear membrane, within which the cell’s DNA is stored and organized.

Question 30

Which of the following is not part of the endomembrane system? A) Lysosomes. B) Mitochondria. C) Rough endoplasmic reticulum. D) Golgi apparatus.

Answer 30

Correct Answer: B) Mitochondria. Explanation: Mitochondria function independently of the endomembrane system; they are semiautonomous organelles derived from endosymbiotic bacteria.

Question 31

Mitochondria are unable to survive outside of eukaryotic cells. If they originated from ancestral prokaryotes, as proposed by the endosymbiotic theory, then why can’t they survive independently? (Select all that apply) A) Mitochondrial genes transferred to the cell nucleus. B) There should be no reason for mitochondria not to survive independently. C) The mitochondrion might not have all its genes; therefore, it cannot perform all its functions if removed from the eukaryotic cell. D) Over time, mitochondria and their host cells evolved to be dependent on each other.

Answer 31

Correct Answers: A), C), and D). Explanation: Over evolutionary time, many mitochondrial genes transferred to the host nucleus, leaving mitochondria dependent on the cell for essential proteins and metabolites.

Question 32

Ribosomes are structures responsible for (BLANK) synthesis. A) Lipid. B) Protein. C) All of these. D) Carbohydrate.

Answer 32

Correct Answer: B) Protein. Explanation: Ribosomes translate mRNA to build polypeptides, forming the proteins essential for cellular structure and function.

Question 33

Which best describes the function of cristae? Select all that apply. A) They are compartments for digestive enzyme storage in eukaryotic cells. B) They increase the capacity of the mitochondria to synthesize ATP. C) They increase the surface area for reactions associated with cellular respiration. D) They provide a location for the light reactions of photosynthesis in plant cells.

Answer 33

Correct Answers: B) and C). Explanation: Cristae are folds in the inner mitochondrial membrane that increase surface area, enhancing the efficiency of ATP synthesis during cellular respiration.